Explanation:

Note: We know that
Expenditure = Price × Consumption
Keeping the expenses constant between price and consumption if one goes up, the other goes down and vice-versa.
Ex. If price goes up by 25% (1/4), then the consumption should go down by
= 1 /4+1 = 1/5 = 20% to keep the expenses same
Here, reduction in price = 25% =  1/4 
= 1 /4-1 = 1/3 = 1 kg.
∴    Increase in consumption will be
Which means kavya initially used to buy 3 kg sugar for 30/-
∴   Initial price of sugar = 30/3 = 10
∴   Reduced price = (100 – 25)% of 10/-
= 75 × 10 = 7.5
or,  7 1/2